The present invention relates to fluid flow machines in general, and more particularly to improvements in fluid flow machines of the type wherein the moving part or parts of the pump receive motion from an electromagnet. Still more particularly, the invention relates to improvements in fluid flow machines wherein an electromagnet is installed in a housing consisting at least in part of a synthetic plastic material and wherein such housing further confines a control circuit for the electromagnet.
It is already known to install the electromagnet of a fluid flow machine adjacent to a partition or wall which forms part of the housing and carries the casing of the pump. The control circuit is normally installed in a housing section which is adjacent to the section accommodating the electromagnet. In a conventional fluid flow machine of the just outlined character, the various actuating or adjusting elements in the form of knobs, switches or the like are disposed at the outer side of a rectangular plate whose inner side carries the components of the control circuit. The plate constitutes a cover or wall which is insertable into a complementary opening provided in the respective end portion of the housing. The housing has a substantially rectangular outline and consists of a synthetic plastic material. The cross-sectional configuration of the entire housing is at least substantially constant. A second wall of the housing, which is disposed opposite the aforementioned cover, is detachable and has a cylindrical extension to form therewith a portion of casing or head of the pump. The electromagnet is secured to a plate-like rectangular support, and those portions of the support which extend beyond the electromagnet are secured to the second wall by screws or similar fasteners. The upper side and the underside of that portion of the housing which surrounds the electromagnet are provided with cooling ribs extending in the axial direction of the electromagnet. The housing is provided with a supporting leg which is spaced apart from and is disposed at a level below the lower set of cooling ribs. The foot comprises two sidewalls which are integral with the housing.
It is well known that an energized electromagnet develops lost heat. The temperature in the region surrounding the electromagnet can reach a value which is excessive for a plastic housing. In fact, the temperature which a plastic housing can stand is relatively low so that a fluid flow machine of the above outlined character can employ a synthetic plastic housing only when the heat losses are relatively low, either because the required output of the pump is low or because the dimensions of the electromagnet exceed the required dimensions. This is undesirable due to excessive space requirements of an overdimensioned electromagnet as well as due to much higher cost and higher energy requirements of such electromagnet. Therefore, conventional compact high-output fluid flow machines employ metallic housings which ensure more satisfactory dissipation of heat than a plastic housing and whose material can stand much higher temperatures than a synthetic plastic substance.